21945697407 has 24 divisors (see below), whose sum is σ = 32414862480. Its totient is φ = 14302967040.

The previous prime is 21945697399. The next prime is 21945697429. The reversal of 21945697407 is 70479654912.

21945697407 is a `hidden beast` number, since 2 + 1 + 9 + 4 + 569 + 74 + 0 + 7 = 666.

It is not a de Polignac number, because 21945697407 - 2³ = 21945697399 is a prime.

It is a super-2 number, since 2×21945697407² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21945697607) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18058 + ... + 210279.

It is an arithmetic number, because the mean of its divisors is an integer number (1350619270).

Almost surely, 2^21945697407 is an apocalyptic number.

21945697407 is a deficient number, since it is larger than the sum of its proper divisors (10469165073).

21945697407 is a wasteful number, since it uses less digits than its factorization.

21945697407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228583 (or 228580 counting only the distinct ones).

The product of its (nonzero) digits is 3810240, while the sum is 54.

The spelling of 21945697407 in words is "twenty-one billion, nine hundred forty-five million, six hundred ninety-seven thousand, four hundred seven".